Abstract: Dielectric nanoantennas have recently emerged as promising alternative candidates to plasmonic systems in the visible range.1 When excited above their bandgap energies, high-refractive-index dielectric nanostructures can highly concentrate electric and magnetic fields within subwavelength volumes while presenting ultra-low absorption compared to metals. In particular, by locally enhancing the incident light intensity, dielectric nanoantennas are expected not only to produce negligible heating, but also boost nonlinear phenomena and surface-enhanced spectroscopies, since their efficiencies increase with the excitation density.

In this presentation, Si, GaP and Ge nanoantennas will be introduced as promising nanosystems for surface-enhanced Raman and fluorescence spectroscopies, second and third harmonic generation at visible wavelengths, and four-wave mixing phenomena.2-6 Fluorescence enhancement factors of over 3000 and harmonic conversion efficiencies of 10-3% will be demonstrated for suitably engineered dielectric nanostructures. Finally, hybrid dielectric/metallic Si/Au nanoantennas will also be analysed.7